The 34-year-old had missed three matches at the beginning of the New Year following his contraction of a strong variant of COVID-19.
However, the Argentina forward returned last week in a substitute appearance at home to Reims, when he set up Marco Verratti for his side's third goal in a 4-0 win just four minutes after coming off the bench.
Pochettino is now satisfied that the former Barcelona man has fully recovered from the virus and is ready to return to the starting 11 against Nice.
The PSG boss has said in the build up to the game: "He trained well this week after having been absent due to COVID.
"He played 30 minutes last week and I think he's fit to start the match against Nice on Monday."
Despite netting five goals in as many games in the Champions League for the French giants this season, Messi has struggled in Ligue 1, where he has managed just one goal in his 12 appearances to date. body check tags ::